NAME

cgttrs - solve one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B,

SYNOPSIS

  SUBROUTINE CGTTRS( TRANSA, N, NRHS, LOW, DIAG, UP1, UP2, IPIVOT, B, 
 *      LDB, INFO)
  CHARACTER * 1 TRANSA
  COMPLEX LOW(*), DIAG(*), UP1(*), UP2(*), B(LDB,*)
  INTEGER N, NRHS, LDB, INFO
  INTEGER IPIVOT(*)

  SUBROUTINE CGTTRS_64( TRANSA, N, NRHS, LOW, DIAG, UP1, UP2, IPIVOT, 
 *      B, LDB, INFO)
  CHARACTER * 1 TRANSA
  COMPLEX LOW(*), DIAG(*), UP1(*), UP2(*), B(LDB,*)
  INTEGER*8 N, NRHS, LDB, INFO
  INTEGER*8 IPIVOT(*)

F95 INTERFACE

  SUBROUTINE GTTRS( [TRANSA], [N], [NRHS], LOW, DIAG, UP1, UP2, 
 *       IPIVOT, B, [LDB], [INFO])
  CHARACTER(LEN=1) :: TRANSA
  COMPLEX, DIMENSION(:) :: LOW, DIAG, UP1, UP2
  COMPLEX, DIMENSION(:,:) :: B
  INTEGER :: N, NRHS, LDB, INFO
  INTEGER, DIMENSION(:) :: IPIVOT

  SUBROUTINE GTTRS_64( [TRANSA], [N], [NRHS], LOW, DIAG, UP1, UP2, 
 *       IPIVOT, B, [LDB], [INFO])
  CHARACTER(LEN=1) :: TRANSA
  COMPLEX, DIMENSION(:) :: LOW, DIAG, UP1, UP2
  COMPLEX, DIMENSION(:,:) :: B
  INTEGER(8) :: N, NRHS, LDB, INFO
  INTEGER(8), DIMENSION(:) :: IPIVOT

C INTERFACE

#include <sunperf.h>

void cgttrs(char transa, int n, int nrhs, complex *low, complex *diag, complex *up1, complex *up2, int *ipivot, complex *b, int ldb, int *info);

void cgttrs_64(char transa, long n, long nrhs, complex *low, complex *diag, complex *up1, complex *up2, long *ipivot, complex *b, long ldb, long *info);

PURPOSE

cgttrs solves one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B, with a tridiagonal matrix A using the LU factorization computed by CGTTRF.

ARGUMENTS

TRANSA (input)
Specifies the form of the system of equations. = 'N': A * X = B (No transpose)
```
 = 'T':  A**T * X  = B  (Transpose)
```
```
 = 'C':  A**H * X  = B  (Conjugate transpose)
```
N (input)
The order of the matrix A.
NRHS (input)
The number of right hand sides, i.e., the number of columns of the matrix B. NRHS > = 0.
LOW (input)
The (n-1) multipliers that define the matrix L from the LU factorization of A.
DIAG (input)
The n diagonal elements of the upper triangular matrix U from the LU factorization of A.
UP1 (input)
The (n-1) elements of the first super-diagonal of U.
UP2 (input)
The (n-2) elements of the second super-diagonal of U.
IPIVOT (input)
The pivot indices; for 1 < = i < = n, row i of the matrix was interchanged with row IPIVOT(i). IPIVOT(i) will always be either i or i+1; IPIVOT(i) = i indicates a row interchange was not required.
B (input/output)
On entry, the matrix of right hand side vectors B. On exit, B is overwritten by the solution vectors X.
LDB (input)
The leading dimension of the array B. LDB > = max(1,N).

INFO (output)

 = 0:  successful exit

 < 0:  if INFO  = -k, the k-th argument had an illegal value